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Architecture and Key Components
Building an EX8200-based Virtual Chassis configuration requires
two 8-slot Juniper Networks EX8208 Ethernet Switches, two 16-
slot EX8216 Ethernet Switches, or a combination of both, and
two XRE200 devices to provide an active/standby pair for control
plane and management plane redundancy.
Ports on the VCCI modules connect to the EX8200 internal REs,
either the EX8208-SRE320 or EX8216-RE320. One internal RE
from each EX8200 chassis is connected to the active XRE200,
while the second internal RE is connected to the standby XRE200.
The two XRE200 devices can also be connected to each other
directly via GbE interfaces.
An optional 1000BASE-X fiber VCCI module can be used to
connect the active and standby XRE200 devices in environments
where the distance between them exceeds the maximum span
of unshielded twisted pair cable—for example, when the EX8200
Virtual Chassis configuration is spread across two buildings.
Juniper Networks Junos
operating system high availability (HA)
®
features such as GRES, NSR, and nonstop bridging (NSB) are
enabled on the XRE200 devices in a Virtual Chassis configuration.
In the event of an active XRE200 failure, the standby XRE200
assumes the active role without impacting network state or
forwarding behavior. Junos OS HA features ensure that the state of
the Virtual Chassis, L2/L3 protocols, and forwarding information
are not lost.
In addition, all Junos OS control plane protocols running on an
EX8200 Virtual Chassis configuration—including 802.3ad, OSPF,
Internet Group Management Protocol (IGMP), Physical Interface
Module (PIM), and BGP—also run on the XRE200, providing
control plane scalability for large core deployments. The EX8200
and XRE200 use the Virtual Chassis Control Protocol to exchange
Virtual Chassis state information.
Active XRE200
2 x 10 Gigabit Ethernet LAG
2
Roadmap
2
EX8200
Virtual Chassis
switch
Intra-XRE200 connection for HA (1GbE)
Active XRE200 to Internal RE connection (1GbE)
Standby XRE200 to Internal RE connection (1GbE)
Figure 1: EX8200 line of Ethernet Switches in a Virtual Chassis configuration
XRE200 Features and Benefits
In addition to control plane scalability, the XRE200 ensures that if one
or more switches in the Virtual Chassis configuration lose connectivity
to the adjacent chassis, access switches connected to the EX8200
Virtual Chassis do not lose connectivity with the network.
The XRE200 also ensures that traffic flowing from one access
switch to any other access switch or to any core/WAN router
connected to the same EX8200 Virtual Chassis configuration are
not affected if the intra-Virtual Chassis connection fails.
Junos Operating System
The XRE200 runs the same Junos OS used by the Juniper Networks
EX Series Ethernet Switches, as well as all Juniper Networks routers
and Juniper Networks SRX Series Services Gateways. By utilizing a
common operating system, Juniper Networks delivers a consistent
implementation and operation of control plane features across
all products. To maintain that consistency, Junos OS adheres to a
highly disciplined development process that uses a single source
2
code, follows a single quarterly release train, and employs a highly
available modular architecture that prevents isolated failures from
bringing down an entire system.
These attributes are fundamental to the core value of the
software, enabling all Junos OS-powered products to be updated
simultaneously with the same software release. All features are
fully regression tested, making each new release a true superset
of the previous version. Customers can deploy the software with
complete confidence that all existing capabilities are maintained
and operate in the same way.
10GbE LAG intra-Virtual Chassis connection
10GbE links
Tra c flow from access to access and access
to core/WAN
Stanby XRE200
EX8200
Virtual Chassis
switch
2 x 10 Gigabit Ethernet LAG
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